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<div> <div class="blockIndicator obsolete obsoleteHeader"><p><strong><span class="icon-only-inline" title="This is an obsolete API and is no longer guaranteed to work."><i class="icon-trash"> </i></span> 已废弃</strong><br/>This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.</p></div></div>
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<h2 id="Summary" name="Summary">概述</h2>
<p>返回一个函数的形参数量.</p>
<h2 id="Description" name="Description">描述</h2>
<p class="note"><code>arity</code>是一个古老的已经没有浏览器支持的属性,你应该使用<code><a href="/zh-CN/docs/JavaScript/Reference/Global_Objects/Function/length" title="JavaScript/Reference/Global_Objects/Function/length">Function.prototype.length</a></code>属性来代替.</p>
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